Cellulose product and method of making same



Patented Feb. 22, 1927.

urrun s'ra'rss ereur OFFIC.

HORACE H. CLARK, OF FAEMINGDALE, NEW JERSEY, ASSIGNOE TO CLARK FIBREPRODUCTS CORPORATION, A CORPORATION OF DELAWARE.

CELLULOSE PRODUCT AND METHOD OF MAKING SAME.

No Drawin g;

in many ways to these; As an example of the best method of practising myinvention at present known to me, I would proceed as In follows:

A bath is prepared offused zinc chloride brought-into solution with anamount of water sufficient. to give a reading of 72 Baum (for heavyliquids) at a temperature of 60 Fahrenheit and to this is added a smallpercentage of phosphorus oxychloride, preferably by taking about 10% ofthe zinc chloride solution ,and 7 adding thereto 3% (of the weight ofthe original zinc chloride reaction resulting usually produces heavyfumes and when the evolution of these has ceased. this mixture is addedto the remaining 90% of the original zinc chloride bath ing untilevolution of hydrochloric acid gas substantially ceases, the resultantbath. of course, containing 100 parts by weight of the zinc chloridesolution and three parts by weight of the phosphorusoxychloride. 'Alarger proportion ride increases translucency and homogeneity of finalproduct. I have used as high as 10%, with varyingdegrees of homogeneityof product particularlyin regard to plastic qualities, but generallyprefer to use the 3% a above indicated.

The cotton fibre paper, preferably .009 of an inch thick; is cut intosheets, preferably dried and heated somewhat above room temperature, andthese sheets are then run successively through the bath of the abovedescribed solution and wound on a hollow mandrel preferably of brass,previously" heated 45 on a steam table to about 1.20 degreesFahrenheit-,the purpose of the heating being to cause the paper toadhere promptly to themandrel. The mandrel may be about 2% inchesinouter diameter or of any size desired for the tubes to be wound thereon;A better product is obtained it the sheets can be wound on the mandrelcold. but the delay in manufacture resulting from this proce-v (lure isat present so great as to render it uncommercial. For the purpose ofmaking solution) 'in phosphorus oxychloride. The

f and thoroughly mixed therewith as by boilof phosphorus oxychlo-Application filed March 8, 1924. Serial No. b97355.

certain optical goods the tubes formed by winding .on the mandrelconsist of eight coils or laminations (resultant thickness of wall about.063 inches). Varyingv portions of the solution absorbed by the paperfrom the bath may be expressed, by adjusting the. pressure of a squeegeeroller bearing on the tube being formed on said mandrel, according tothe character of the finished product desired, and the degree of finalimpregnation by the solution thereby varied.

The mandrels and tubes wound on them are then hung 'in'the factory roomover a No. 1 tank into which the drippings from the tubes collect. Theproduct of each day is allowed to hang thus over night. Little changeresults in the thickness of wall of the tube during this curingoperation,- but, during the first part of this curing or drying, say thefirst part of an hour, the material 75 softens perceptibly so as to beeasily and deeply scored by the pressure of the finger nail and then,during the latter part of the curing or drying and perhaps during thelatter part of the first hour. it ha rdens so 30 that at the end of thehour it is much harder than was the original paper.

The following morning the mandrel s, and tubes still on them. aresubmergedfor abouttwo hours in said No. 1 tank, in which the solutionhas been collected from the drip and washings of previous operations.This solution becomes progressively stronger, and

,cally cease and the tubes can then be stripped from the mandrels. Thetubes so removed from the mandrels are next placed in jute bags and thebags and contents immersed in No. 2 tank which contains a like solutionof zinc chloride and oxychloride, the limit of concentration being 20Baum. They 1 are left in this No. 2 tank two days and the bag thenwithdrawn and suspended over No.

2 tank to allow drip from it and its contents into the tank forabout/one hour.

The bag and contents are next submerged in a No. 3 tank in hichoriginally fresh water was placed- .ihis water is changed about once aweek, it is gradually contaminated by accumulated drippings from thetubes, and the weak solution then taken out of No. 3 tank is placed inNo. 2. Submersion in tank No. 8 continues for about two days.

The bag and contents are next transferred to a No. 4 tank, which issupplied with ordinary running water, for about two days.

The purpose of the above washings is to remove from the tubes thesolution with which the paper was impregnated before wrapping on themandrels and the comple tion of such removal may be tested from time totime by immersion of sample tubes in a very weak ammonia solution. Ifthe solution becomes cloudy it means that the washing has not beensutlicient for the best high grade uses and must be. prolonged orotherwise modified to secure the desired result.

After removal from No. 4 tank the bag and contents are allowed to standuntil the tubes are dry enough to be handled conveniently. Staves arethen put in each tube to prevent it warping during the completion of thefinal drying, and tubes so mounted are put in the factory loft andallowed to remain there for about 2 days to complete the curing anddrying.

The various draining and drying steps above described may be performedin special rooms, the temperatures of which can be artificiallycontrolled, and in such case I have found an atmospheric temperature of90 degrees Fahrenheit to give the best results. \Vhile I have obtainedthe best results and are left there from the particular above describedprocess of winding the tubes and subsequent treatment of them, otherstandard methods of procedure employed in making so called in durated orvulcanized fibre could be substituted for the special procedure I havehere described in detail.

After removal from the mandrcls the tubes shrink in diameter during thesuccessive stages of the washing and drying process according to thedegree of original saturation, which is controlled by the makeup of thesolution, the time of original soaking and the pressure of the squeegee.It a light pressure was used, such as is merely sutlicient to preventthe formation of blisters between laminations, the highest degree ofsaturation secured in the bath persists and,

apparently as the result of the action of the solution on the cellulose,a shrinkage of about 33% in tube diameter obtains by the time the.curing process is completed. If a high squeegee pressure is used and alarge part'of the solution thus expressed from the tube as it is formedon the mandrel, only a low percentage of saturation results and the tubemay not shrink more than 5% to 6% in diameter during the entire process.The average reduction of wall thickness generally is something over 33%,the standard thickness of wall of such a finished tube beiue .039inches. whereas the original thickness, as above given, was .06?)inches. This shrinkage is highly important as improving the ultimatestructure of the product.

The eil'ect of increasing: the proportion of oxychloride above thatgiven in the preferred formula herein stated is to increase thetranslucence of the finished product, and also its plasticity under diepressure, its flexibility under distortion and its tensile strength.

The eii'ect of the higher degrees of saturation resulting from immersingthe paper in a solution of any given formula in the original bath issimilar to that of the increase of the oxychloride above stated.

The material flows or stretches under pressure in the die even when itis practically cold. The tube sections it'placed in heated, slightlyflaring die recesses, do not touch the walls of the die originally and,when expanded by pressure of an unheated rubber former until they comein contact with the heated die Walls, set in this expanded condition,doubtless as the result of the effect of the heat derived from the die.The greater the amount of heat applied, however, the more readily thematerial flows under pressure.

The main advantage of washing the tubes in progressively weakeningsolutions of the zinc chloride and phosphorus oxychloride is not whollyclear to me, as yet. I believe the successive washings in graduallyweaker so lutions of the treating chen'iical helps to prevent excessivehydrolyzation and adsorption of treating chemical (or ions thereof) inthe cellulose material in such manner as otherwise might excessivelymincralize the final product. Certainly it enables me to recover allthat is possible of these solu-' tions so that a given body of theliquid, after bemg stepped up in strength by its progress from tank No.3 to tank No. 1.

may be further concentrated and added to i the impregnating baththroughwhich the paper 18 passed before winding on the man drel, or thechloride and oxychloride con-- tents thereof otherwise recovered.Similar considerations of economy dictate the dcscribed method ofrecovering the drippings from the tube. All these drippings and washingsmight be thrown away and fresh water used in each washing tank if theconsequent waste were commercially permissible. v

The product resulting from the above described process, or from anygcnerall y similar one involving only immaterial modificathe process ofmanufacture, as does the in-' durated or vulcanized fibre hithertoknown. It is somewhat hydroscopic. It will take and hold any ordinarydye, paint or lacquer.

It has a tensile strength and an elastic limit which compare favorablywith those of the best. vulcanized fibre product now on the market.

It has in high degree the property of flowing under pressure, as in adie. For e1;- ample, tubes formed of it may, without injury, be quicklyspun or pressed in a die down to about one half their original diameter,whereas tubes formed of the best other form of indurated fibre known tome cannot be reduced in diameter to anything like that extent except byvery careful manipulation in a heated die performed so slowly that theheat of the die scorches the product and there is an incipient crushingof the fibre. Similarly, tubes of my material can be easily expanded 22percent in diameter, while tubes of the best other indurated fibreknownto me cannot be expanded beyond 13 percent of their originaldiameter. The best results under compression are obtained with theproduct dry, while the best results under expansion are obtained whenthe product is. moist. Also strips of my material .300 inch thick cansafely'be rolled down to .187 inches in thickness without injury.whereas similar strips of indurated fibre heretofore on the marketcannot be so rolled down over .075 inch, without breaking up. In thecase of sheets the improvement in this regard is still more marked whenmy improved n'iaterial is used, as compared with best varieties of otheriudurated fibre products known to me. Another novel characteristic of mymaterial 1sthe substantial freedom of sheets from blistering in allstages of manufacture, such blistering being a source'of great waste andloss in the manufacture of sheets out of other forms of indurated'fibre,even when the best grades of paper are used, and becoming practicallyprohibitive. when an attempt is made to use The material sets inwhatever form it'is thus i'nolded, it does not become brittle under thecontinued application of heat, as is the case with the ma ority of othercellulose products made from fibre and it does not warp to anyappreciable extent has practically no porosity, but I after suchsetting,

microscope they disclose a much less striated structure than dospecimens of the best other form of indurated fibre known to me.

Microphotographs of cross sections of the mass also show scattereddeposits of a white powder, the nature and origin of which have not yetbeen determined.

It may be made pliable to the highest degree .when slightly humid ifcomplete saturation was employed in the initial treatment, and tolesser, degrees when such saturation-was less complete. Pieces .045 inchin thickness have been bent sharply cold and when longitudinal sectionsof the mass are examined under the through 180 degrees back and forthwithout showing racture at the pointof bending. It is qulte resilientwhen cold and practically resumes its original shape after moderatebending, but if bent hot it takes a permanent set.

It may be given high non-conducting and dielectric properties when pure,and these may be further heightened by mixing other suitablenon-conducting materials with the original fibre.

Its texture is such that it can be easily and accurately machined withvery little wear on the cutting edges of the tools used and itssurfacesare capable of receiving a high polish, as by butting or otherusual polishing process.

\Vhen its surfaces have been treated with the copper salts solutiondescribed in my application, Serial No. 697,956 filed of even dateherewith, pieces can be quickly welded together under pressure so astoform one practically homogeneous body of great mechanical strength andtoughness so that thin-walled articles of fairly diversified contour,such as goggle frames, made by joining pieces of it, can be thrownviolently on a stone floor, or against a sharply serrated'steel surface,without developing fracture or substantial disintegration.

It is understood, of course, that the preferred process herein describedis subjected to variations to obtain various etfects, by modifying theproportions of the constituents, the order or character of certain ofthe described steps, degrees of heat or moisture employed, etc. withoutdeparting from the essential novelty of, my discovery or invention, andthat chemical or other equivalents may be substituted for some or all ofthe ingredients mentioned with like product obtained which, whilepossibly interior to the best form of my invention in some features.would still involve some or all of the novel principles hereindisclosed.

The herein described product has a tensile strength of from 12,000to'15,000 pounds per square inch of cross section accord to the careexercised, and the perfection at taincd, in its manufacture, and doesnot be gin to develop any permanent elongation until subjected to about75 per cent of the breaking strain. Uncalendered sheets develop anelongation of about 5 percent before rupture. \Vhen calcndered, theclongation reaches 10 percent.

Having described my invention, I claim:

1. The herein described process of producing indurated fibre whichcomprises impregnating a body of cellulose with a solution to which hasbeen added a phosphorus oxychloridc, washing out said solution anddrying the product.

2. A process such as set out in claim 1 in which the degree of saidimpregnation is carried to the point of practical saturation with thesolution.

3. A process such as set out in claim 1 in which said washing is done insuccessive steps.

4. A process such as set out in claim 1 in which said washing is done insuccessive steps and the baths for said washing steps, except the last,consist of progressively weaker solutions similar to the originalimpregnating liquid.

5. The herein described process of producing indurated fibre by treatingfelted cotton fibre, which comprises impregnating sheets thereof with asolution to which has been added a phosphorus oxychloride while beingassembled in a laminated structure, washing out said solution and dryingthe product. ,6. A process such as set out in claim 5 in which thedegree of impregnation is carried to the point of practical saturationwith the solution.

7. A process such as set out in claim 5 in which said washing is done insuccessive steps. l

8. A process such as set out in claim 5 in which said washing is done insuccessive steps. and the baths for said washing steps, except the last,consist of progressively weaker solutions similar to' the originalimpregnating liquid.

9. The process of treating cellulose which comprises iu'ipregnating thesame with a so-v lution containing a major proportion of a metallicchloride in water to which has been added a minor proportion ofphosphorus oxyehloride. compressing the same into a mass of induratedfibre, washing out said solution and drying the product.

10. The process of treating cellulose which comprises impregnating thesame with a solution containing a major proportion of zinc chloridein'water to which has been added a minor proportion of phosphorusoxychloride. compressing the same into a mass of indurat'ed fibre,washing out said solution and drying the product.

11. A process such as set out in claim 9 in which the degree ofsaturation'is' carried to the point of practical saturation with thesolution.

12. A process such as set out in claim 9 in which said impregnatingliquid contains about 100 parts by weight of a solution of said metallicchloride and water. of a density of 72 degrees Baum at degreesFahrenheit. to which has been added about :3 parts by weight of saidphosphorus oxychloride.

13. A process such as set out in claim 9 in which said washing is donein successive steps.

1 1. A process such as set out in claim 9 in which said washing is donein successive steps and the baths for said washing step, except thelast. consist of progressively weaker solution similar to the originalimpregnating liquid.

15. The herein described process of treating felted cotton fibre whichcomprises impregnating sheets thereof with a solution containing a majorportion of zinc chloride in water to which has been added 'a minorproportion of phosphorus oxychloride while being assembled in alaminated structure, washing out said solution and drying the product.

16. The herein described process of treating felted cotton fibre whichcomprises impregnating sheets thereof with a solution containing a majorportion of zinc chloride in water to which has been added a minorproportion of phosphorus oxychloride while being assembled in alaminated structure, washing out said solution and drying the productafter compression and conversion have produced a substantiallynon-laminated mass of indurated fibre.

17. A process such as set out in claim 15 in which the degree ofimpregnation is carried to the point of practical saturation with thesolution.

18. A process such as set out in claim 15 in which said washing is done.in successive steps.

19. A. process such as set out iirclaim 15 in which said washing is donein successive steps and the baths for said washing steps. except thelast. consist of progressively weaker solutions similar to the or ginalimpregnating liquid.

20. Av particular form of the hereindescribed process in which theimpregnated sheets of felted tightly intoa tube on a mandrel, driedtherecellulose fibre are woundon and then dipped in a mixture of zincchloride, and water to which has beenadded an oxychloride of a densitynot exceeding degrees Baum at room temperature,-to fa- (ci-ilitatestripping said tube from said manrel. i

21. A product of the herein claimed process, being a solid substantiallyhomogeneous body of approximately pure indurated cellulose fibre havingat least a tensile strength of about 12,000 pounds per square inch ofcross section.

22. A product of the herein claimed process, being a solid substantiallyhomogeneous body of approximately pure indurated cellulose fibre havinga tensile strength in excess of 12,000 pounds per square inch of crosssection and having a specific gravity of about 1.25.

23. A product of the herein claimed process, being a solid substantiallyhomogeneous body of approximately pure cellulose which is plastic whensubjected to ordinary die pressures at room temperature.

24. A product of the herein claimed process, being a solid,substantially homogeneous body of approximately pure cellulose fibrewhich is highly elastic at room temperature but takes a ermanent setwhen distorted at suitabl hig er temperatures.

25. ess, being a solid body of approximately pure indurated cellulosefibre which is highly translucent throughout.

26. A-product of the herein claimed'proc ess, being a solidsubstantially non-porous body of approximately purecellulose havingflexibility at room temperature when slightly humid, such that a thinsection thereof may he flexed sharply back and forth about fifty timeswithout developing fracture at the point of flexure.

27. A product ess, being' a solid body of approximately pure cellulosefibre pliable at medium temperatures and maintaining such pliabilityafter prolonged heating.

product of the herein claimed procof the herein claimed procs 28. Aproduct of the herein claimed process, being a solid consisting ofsubstantially homogenized cellulose fibre, together with residualamounts (about .10 per cent) of modifying materials of cementitiousmatter,

. such as zinc and phosphorus compounds,

which solid is semi-plastic under mechanical stress, somewhattranslucent, substantially uninjured by severe flexure, capable ofassuming a plastic set under the action of heat, having an elastic limitofabout 9,000 pounds under tension and a tensile strength of about12,000 pounds with about 5 per cent elongation before fracture, capableof great distortion under lateral pressure and capable of being swagedinto modified shapes without separating the initial laminae ofconstruction and having a specific gravity in excess .ened baths of thesame solution.

' 30. A process such as defined in claim 29 in which said bath is formedby initially mixing saidoxychloride with about 10 per cent of theoriginal zinc chloride solution,

and then adding said mixture to the remaining 90 per cent ofsaid zincchloride.

. 31. A' process such as defined in claim 29 in which the cellulosefibre originally saturated is in the form of sheets of paper, and

in which such saturated sheets are compact ed together by winding on amandrel under pressure from an adjacent roller.

32. Aprocess such as defined in claim 29 in which the mixing of the bathconstituents is effected by boiling until the evolution of hydrochloricacid gas substantially ceases.

HORACE H. CLARK.

